Use signedxml to validate signatures

Makefile

@@ -13,6 +13,7 @@ init:
 	go get github.com/nu7hatch/gouuid
 	go get github.com/kardianos/osext
 	go get github.com/stretchr/testify/assert
+	go get github.com/ma314smith/signedxml
 
 vet: init
 	@echo "$(OK_COLOR)==> Go Vetting$(NO_COLOR)"

xmlsec.go

@@ -1,11 +1,16 @@
 package saml
 
 import (
+	"crypto/x509"
 	"errors"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"strings"
+
+	"encoding/pem"
+
+	"github.com/ma314smith/signedxml"
 )
 
 const (
@@ -67,31 +72,42 @@ func sign(xml string, privateKeyPath string, id string) (string, error) {
 // `publicCertPath` must be a path on the filesystem, xmlsec1 is run out of process
 // through `exec`
 func VerifyResponseSignature(xml string, publicCertPath string) error {
-	return verify(xml, publicCertPath, xmlResponseID)
+	return verify(xml, publicCertPath)
 }
 
 // VerifyRequestSignature verify signature of a SAML 2.0 AuthnRequest document
 // `publicCertPath` must be a path on the filesystem, xmlsec1 is run out of process
 // through `exec`
 func VerifyRequestSignature(xml string, publicCertPath string) error {
-	return verify(xml, publicCertPath, xmlRequestID)
+	return verify(xml, publicCertPath)
 }
 
-func verify(xml string, publicCertPath string, id string) error {
-	//Write saml to
-	samlXmlsecInput, err := ioutil.TempFile(os.TempDir(), "tmpgs")
+func verify(xml string, publicCertPath string) error {
+	pemString, err := ioutil.ReadFile(publicCertPath)
 	if err != nil {
 		return err
 	}
 
-	samlXmlsecInput.WriteString(xml)
-	samlXmlsecInput.Close()
-	defer deleteTempFile(samlXmlsecInput.Name())
+	pemBlock, _ := pem.Decode([]byte(pemString))
+	if pemBlock == nil {
+		return errors.New("Could not parse certificate")
+	}
 
-	//fmt.Println("xmlsec1", "--verify", "--pubkey-cert-pem", publicCertPath, "--id-attr:ID", id, samlXmlsecInput.Name())
-	_, err = exec.Command("xmlsec1", "--verify", "--pubkey-cert-pem", publicCertPath, "--id-attr:ID", id, samlXmlsecInput.Name()).CombinedOutput()
+	cert, err := x509.ParseCertificate(pemBlock.Bytes)
 	if err != nil {
-		return errors.New("error verifing signature: " + err.Error())
+		return err
+	}
+
+	validator, err := signedxml.NewValidator(xml)
+	if err != nil {
+		return err
+	}
+
+	validator.Certificates = append(validator.Certificates, *cert)
+
+	err = validator.Validate()
+	if err != nil {
+		return err
 	}
 	return nil
 }